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Lexus RX 400h: Problems & Solutions

Karen_SKaren_S Member Posts: 5,092
edited March 2014 in Lexus
Talk about RX 400h problems and share solutions here.


  • dmbfloridadmbflorida Member Posts: 38
    I have not gone in for the free "30 day" inspection/evaluation of my 400h because I have only about 300 miles on it.
    However, on about 3 or 4 occasions, I have not been able to start my car immediately because the ignition switch does not "turn on" (get a Ready signal). I have tried all possible lateral moves of the key plus pushing in and out of the key in different combinations. The key seemed blocked.
    Finally, after 4 - 8 times of attempting to turn the key in the above manner, the key did turn appropriately and the power system came on. I also have noticed that my Ready signal is 30 seconds or so slower to come on sometimes than someone else's 400h.
    Has anyone had this experience? Does it sound like a loose ignition switch and therefore, should I go in for service ASAP? I don't want to be stranded somewhere.
  • wwestwwest Member Posts: 10,706
    From the RX400h owners manual. Page 418 left column, top...

    "Driving conditions where the steering wheel must be turned frequently may cause an overload to the electric power steering system. The system will reduce assistance for some time to prevent the power steering from overheating. In this case, you may feel some resistance when turning the steering wheel though it is not a malfunction."

    And some of you didn't believe the RX330 AWD system timed out after 45 seconds to prevent the ABS pumpmotor from overheating.
  • wwestwwest Member Posts: 10,706
    Page 451 of the RX400H owners manual, left column:

    " !CAUTION

    Under certain slippery road conditions, full traction of the vehicle and power against drive wheels cannot be maintained, even though the traction control system is in operation.."

    Anyone care to guess what this statement might mean??
  • maxamigomaxamigo Member Posts: 72
    It sounds like a CYA statement.
  • rx400_ownerrx400_owner Member Posts: 59
    Those of you experiencing poor performance might ask your dealers to try the ISC Learning proceedure which reinitializes the the idle speed control. It is in TSIB EG010-05. This is something that can be necessary if the 12 V battery dies (and possibly that happens during shipment or prep of some of the cars).

    Some of the things this can cause are poor fuel economy, engine running too often and excess noise at idle.

    The info came from a post on another board. It didn't say that it could cause the lurch some here have complained about, but it seems possible that engine idle being messed up might lead to that behavior as well.

    This or something like it would explain why our experiences with this car vary so widely.
  • caps04caps04 Member Posts: 6
    I have 700 miles on my 400h but horrors of horror, on and off (about say 10 times) I have floored the accelerator (not totally, about 75%) to test the acceleration...which is awesome. I can't say I redlined it (though can't tell as there is no tachometer) but is it REALLY BAD for my engine break in and long-term car health?

    Also, some people have mentioned they are getting 27+ mpg within the first month of owning the vehicle. I can't seem to breach the 24 mark. Should I get it checked by the dealership just yet? I do try all the tricks to keep the ICE off the back.

    Thanks for your suggestions in advance.
  • hendjazhendjaz Member Posts: 155
    My apologies for double posting this message but not sure which thread it is most pertinent to and would like any relevant feedback that anyone may have.

    We may be taking delivery soon of a new 400h and then taking off immediately for a family vacation that might quickly add 1500-2000 miles to the RX. For the most part we would not be near any Lexus dealers during the trip although a greater probability of being near some toyota dealers. Are there any reports that anyone is aware of significant or debilitating problems arising in the 400h in the first 2000 miles or so? I read of someone's A/C going out but any others to be aware of that could affect the drivability of the vehicle? Thank you.
  • wwestwwest Member Posts: 10,706
    gets 28 MPG hwy at 75 MPH....

    But it doesn't weigh 2 tons, accomodate 4 adults + luggage comfortably nor can it handle winter roadbed conditions as well even though it is also AWD.

    28 MPG hwy is pretty impressive for a vehicle equivalent to my RX300.

    But I'd still like to know what's going on with the city fuel economy. Not saying the city MPH is shabby by any means, just not what I would expect in light of the hwy MPG.
  • gunnergunner Member Posts: 10
    8-31-05 I took my rx400h to keyes Lexus and got nothing from the factory rep about the 19-20 MPG. He said that in was with in specs. I specifically asked you are saying that you can do nothing to improve the gas mileage and he just repeated his jargon. :lemon: :lemon:
  • eman5eman5 Member Posts: 110
    My kids are prone to removing their seatbelts once we've arrived at their slow drop-off line, so they can start getting their school stuff together, so they can speed their departure and everyone else in the line's departure-- and that darned bell starts going off. Is there a fuse I can pull to disable this "safety" feature?
  • maxamigomaxamigo Member Posts: 72
    I got 28mpg+ on a 2.5hr trip by driving 55-60mph on country roads next to interstate. It's difficult to resist the temptation to drive at 75-80mph on interstate (70mph state limit) which would drop mpg to 26+mpg.

    Just changed oil (4,300 miles) to Mobil-1 gold cap and early in-city number showed an increase in mpg, so I'd expect better numbers in future trips. We're up for a 2,800mile trip next week, on interstates hwy.
  • mkkidmkkid Member Posts: 11
    I've encountered periodic problems filling my 400h. Auto cutoff on pump nozzle shuts off after pumping a gallon or less. This has happened at several stations, but seems more prevalent at Costco. Attendants blame it on design of filler tube on car; anyone else having this problem? :(
  • mirexmirex Member Posts: 68
    Had this problem happen only once. I removed the nozzle and re inserted it and it worked fine. Have fueled up in Washington, Oregon, and California with temperatures as high as 97 degrees. I have used mostly Chevron with some Shell, Texaco, and Union 76. No Costco or Safeway.
  • edman3edman3 Member Posts: 1
    Hi gunner:

    I've just put my $500 deposit down to reserve an RX400h with my local Lexus dealer last weekend. Since then, I've heard a lot of negative utterances from 400h owners who are getting unsatisfactory mileage, some as low as the low 20s.

    Now I have to decide what to do. Take back my $500 and start all over again?? The Prius, which I rented was nice, but had ZERO acceleration and no luxery or size. I did not consider it safe on a 65 mph hwy.

    I've also heard of some owners getting in the upper 20s - like 28+.

    What's really going on here? Any thoughts?

    Edman rcons/emo_confused.gif
  • stevedebistevedebi Member Posts: 4,098
    "What's really going on here? Any thoughts? "

    Two issues:

    1. Driving style. With a hybrid, you can drive very conservatively and get much better mileage.

    2. Short trips are very bad on MPG for hybrids. If your use is mostly in town on short trips of less than 10 miles or so, your MPG may suffer.

    If you are considering the RX400 for just MPG, know what you are getting into. If you drive it like a 330, you will most likely not achieve more than mid 20's MPG. But you will have the latest technology and more power than the 330.

    Don't buy it expecting really good MPG; it is still a 4000+ lb boxy vehicle with a V6 engine. Most drivers appear to be able to achieve 27-28 MPG, which is better than the 330 by 15 % or so. But one has to drive for MPG, not "spirited driving".
  • katzjamrkatzjamr Member Posts: 146
    when this happens i pull the nozzel back from the gas filler opening about an inch and that usually takes care of it. or a slower fill rate. dont have the problem on my 400h, but has happened on my other trucks. I think its more the variability of the pumps you go to .
  • wwestwwest Member Posts: 10,706
    If you drive mostly highway (not heavy traffic stop, slow, go) or freeway miles you will be very pleased with an RX400h. Reports seem to be that it gets 28 MPG or better in those circumstances.

    No one seems to know why, no explanation forthcoming from Toyota or Lexus, but unlike the Prius, the best city, stop and go traffic, mileage appears to be 24 MPG or less.

    Note that neither of these are "bad" numbers, just not what Lexus and Toyota led the buying public to expect.

    My best guess is that the ICE must be kept running, or run more often, just to keep the catalytic converter up to optimum operating temperature. With the Lexus there is also the possible issue of the need to keep the engine water jacket temperature elevated to a level that will best accomodate the optimum operation of the climate control system's reheat/remix air conditioning cycle.

    The Prius, being a Toyota, cares not so very much about discomforting the passengers slightly so it has a c-best setting to allow the climate control to operate in economy mode, bypassing the reheat/remix cycle altogether.

    I was recently informed by Lexus that the C-best option will not be made available for the RX400h, but maybe the HL will have it.

    Additionally the Prius has an extra catalyst stage which traps the unburned hydrocarbons until the catalyst is up to temperature and then opens a flapvalve in the exhaust path so those can be burned.

    My guess is that upscaling the Prius' catalyst technique from an I4 of ~1 liter to a V6 of 3.3 liters didn't work out.

    So since the engine must typically run continuously for highway duty and sometimes (often??)"uselessly" in the city insofar as motive force is concerned the city fuel economy suffers.
  • dadcatdadcat Member Posts: 29
    A similar thing happened to me, coincidently while at Costco in NJ, while the gas attendant was filling it a few weeks ago.This resulted in a spill of fuel onto the ground and a very difficult time filling the tank. At that time, I had opened the fuel door with the engine running, while waiting a few minutes for the car in front to complete its fill-up. I later read the owner's manual (p.153) and the yellow CAUTION label on the inside of the fuel door, that completing the refueling of the vehicle within 30 minutes of opening the fuel door is necessary, otherwise an overflow of fuel will result. An internal valve closes after 30 minutes causing the fuel to backup. The manual says to replace the gas cap and close the fuel door to reset the internal valve. I suspect the internal valve helps to minimize the internal pressure whoosh when opening the gas cap and achieve the SULEV rating.
    I did not have the fuel door open for anywhere near 30 minutes, but the Lexus timing might have been changed to something shorter (10 minutes?). Since that time I haven't had any refueling problems at Costco, because I do not open the fuel door until I am ready to refuel and the engine is shut off.
  • mirexmirex Member Posts: 68
    I just returned from my 3rd round trip in my 400h between Seattle and Portland and once again got 30.0 mpg per my navigation screen. On my return this morning the temperature was in the low 60's so I had my AC off. Still got the same mpg.

    The more in city driving I do lowers my average mpg. My calculated mileage through 6000 mile is just under 27 mpg.

    All of the above is between 5 and 6 mpg better than in my 2003 RX300 and this car weighs more and the power increase is quite noticible.

    We stayed with a friend in Vancouver, WA who lives 5 minutes from work. He bought the RX330 which is the right car for him. I would buy my 400h again as would he buy the RX330. Determine what your driving pattern will be and buy accordingly.
  • roycrawfroycrawf Member Posts: 4
    Just found your message and, yes, our ignition switch also locked up. Car was about 1 month old with about 1000 miles. Tried everything to get it to turn. Wiggled steering wheel, wiggled shift lever, foot on brake, prayed, etc. Nothing. Called local dealer. They asked us to go thru the same routine. Sill locked up. They finally said we would have to call Lexus roadside service. Road side service had us go thru the same routine and said they had never heard of this problem before. They finally said they would send someone to check it out. When the truck came, the two of us tried for another 1/2 hour, still with no success. He was about to tow the car to a repair facility when I mentioned that the roadside service person had mentioned something about jumping the battery. Neither of us could figure out what that would have to do with it but figured why not. He jumpered the battery and still nothing. Just as he was about to disconnect his battery I tried one more time and the ignition switch worked absolutely normally. This is after probably 1 hour of trying to turn the key. Lexus (dealer) claims there is no electrical lockout on the ignition so there cannot be any reason why jumpering the battery would have made any difference. Ignition switch has worked normally since (about 1 month, 800 miles). Since it is an "intermittent" problem we will have to wait until it happens again, then they will haul the car in and try and figure out the problem. Just hope it doesn't happen in some dark, lonely location.


    Love the car, 27 mpg (calculated) commuting and trips (to Tahoe - 6000 ft climb). Our 2002 Highlander was getting 18/21 so am pleased with the mileage.
  • mydquinmydquin Member Posts: 8
    The gas mileage issue is not a problem with the car. It is a problem with people not understanding how the EPA ratings work. Cars don't get the numbers published by EPA. My 400h has been getting in the 22-24mpg range in city. However, I make frequent 1-3 mile trips. I got about 26mpg on the highway, much of that driving faster than 70mph. When I drive 45mph for extended periods, I get closer to 30mpg. Thus I am averaging around 25-26mpg.

    On the other hand, look at consumer reports' real world mpg ratings for the Rx330. Making those same in-town 1-3 mile trips, I could expect somewhere around 12mpg. On the highway, I could expect somewhere around 26mpg for an average of 18mpg.

    The bottom line is that you can expect significantly more power with the 400h with about 30-40% better gas mileage. Depending on the cost of gas, that will add up to somewhere around $6K and $12K in gas savings & significantly less air pollution over the life of the car.
  • eschw999eschw999 Member Posts: 2
    I am thinking about the lexus rx400h. I just drove one today, and really liked it. I was wondering if anyone has problems with the armrest connected to the driver's seat - i thought it was kind of narrow. Has anyone gotten an aftermarkedt armrest, or modified the current one in any way???
  • rzurekrzurek Member Posts: 1
    Purchased Lexus 400h 10/9/05, less than 90 miles that same day and "Check Engine" light came on. Also, sensed some missing (may be due to the fact engine fuel mixture was running lean or rich). Drove to dealer this morning, they said bad oxygen sensor and will need to order replacement part. Gave loaner and part should be delivered tomorrow.
  • kaperinokaperino Member Posts: 19
    This is not the message you are looking for as it is not technical in nature, but I can't resist advocating for a child.

    Why don't you pull the “parent” fuse and insist the children not remove the belt until you are fully stopped? Even a small bump from behind can injure a small child and change their lives forever.
  • woorheewoorhee Member Posts: 1
  • m2inorm2inor Member Posts: 4
    I've got 4800 miles on my 400h, and my check-engine light came on today as well. I though it may be related to the 5000mi checkup warning, but a call to the dealer said - not likely.

    Service tech said that I shouldn't take any long trips until it is checked out, and as long as it wasn't blinking, it was OK to drive.

    With the holidays coming up this week, I'm not able to get the car to the dealer for service until a week from now.

    I hope it is something as simple as an oxygen sensor, and not something more serious.

  • lexrexbluelexrexblue Member Posts: 38
    I had a similar problem the other day. I also tried pulling on the steering wheel. I actually dialed Lexus service after 8 tries. After the phone rang I was able to turn the key. The car was going in for service that day anyway, but they couldn't replicate the problem. Hopefully it won't happen again.
  • roycrawfroycrawf Member Posts: 4
    After 5000 miles my ignition switch problem has not repeated itself so maybe once you get past a lockup it doesn't repeat. We will see. Seems to me the original poster had the problem repeatedly and like you she could get it to work after a few tries. Don't know if she is still having the problem.
  • lexrexbluelexrexblue Member Posts: 38
    Has anyone else turned on their car and gotten the message Check Hybrid System? It happened to me this morning. Although it has been cold and snowy, the car was inside the garage where it was 65 degrees. I couldn't reach the service department so I drove it to work anyway. The message returned when I turned it back on 6 hours later. But when it was turned off at the dealer, the message disappeared. I don't know what to think.
  • lxpatellxpatel Member Posts: 34
    Thank you for such quick reply on the post
  • hibredhibred Member Posts: 4
  • bobgail1bobgail1 Member Posts: 4
    On my rx300, there is a trip timer on the display. It is nice to know how much time has elapsed taking a local trip. Resets after car is turned off. Is there such a timer on the 400H? Can't seem to locate it.
  • mydquinmydquin Member Posts: 8
    FYI, RX400h tops Consumer Reports' SUV reliability ratings.
  • desoto1desoto1 Member Posts: 2
    I am trying to decide between an rx and rxh. I have read the discussions but still haven't made my mind up. While test driving the rxhybrid I thought I could feel it change between gas and electricity while on the road....a slight "shifting" feel. Is this it annoying to anyone? I just don't know if it would be best to stick with the rx.
  • katzjamrkatzjamr Member Posts: 146
    There are times when you might feel it, more at low speeds for me, but it is usually seamless. Premium gas makes the change more abrupt in my 400h. What you will feel in a 400h is the silky smooth CVT, more power, and i think better handling.
  • desoto1desoto1 Member Posts: 2
    Are there any other cons you think other than the gas milage being less than what's stated? I am not as concerned about the difference in the price between the rx and rxh...I just don't know if I should stick to the rx since it is "tried and true."
  • stan17stan17 Member Posts: 3
  • stan17stan17 Member Posts: 3
    I owned an rx 330 and put 85,000 trouble free miles on it. I now own an rx400h and only have 1100 miles on it. I like the 400h even better than the 330. The " transmission" is smoother and the pick up is faster. The engine kicking in and out is not a problem. The 8 year warranty on the hybid part of the car eliminated in my mind the risk with the hybrid. You can not go wrong with either model.
  • wwestwwest Member Posts: 10,706
    At the moment all Toyota/lexus 5-speed transaxles (2002-2005,2006??) seem to have the potential to exhibit a problem referred to as engine hesitation. Some owners experiencing this problem claim it is potentially dangerous or hazardous.

    Several TSBs, and/or revisions to the original one first issued in early 2003, are available describing the three commonly occuring circumstances under which it is deemed most likely to occur.

    To date there have not been enough "votes" to state that the 06 models do or do not have the same problem.

    So in the meantime I would vote for the RXh.
  • ke2feke2fe Member Posts: 37
    After I mark a location in the nav system, how is a local name assigned to this location? eg. "mary's house"
  • satoosatoo Member Posts: 1
    My new 400h has a horrible musty smell when the A/C is turned on after restarting. My neighbor has the same problem. The dealer has tried twice to remove the odor but has not been successful in detecting the source. Has anyone else experience a foul odor emitting from the vents when the A/C is turned on after the vehicle is stopped?
  • wwestwwest Member Posts: 10,706

    Go to and read up on their EED, electronic evaporator dryer.

    Google for:

    demist nippondenso

    Turn the A/C off unless you need it for cooling.
  • stan17stan17 Member Posts: 3
    I want to buy a bluetooth telephone. I have service with Verizon. Please advise
  • dale11dale11 Member Posts: 2
    My wife's 400h cruise control will vary 6-8 MPH on uneven roads. It has been back to Lexus 4 times, checked by their regional specialist. It is most prevalent when cruise is set to 55 MPH which is best speed for top MPG (about 27-29). I just got a call from Lexus headquarters in CA telling me that this is a characteristic of the vehicle and that is the way it works and they will do nothing about it. I find it pretty poor that my 2005 Prius does not have the problem and my sisters 2006 Toyota Highlander Hybrid doesn't have the problem but a $50k Lexus doesn't even have a cruise control that will work.
  • wwestwwest Member Posts: 10,706
    I wouldn't surprised at all if the RX400h's cruise control is slightly biased toward fuel economy rather than exact speed maintenance.
  • dale11dale11 Member Posts: 2
    Fuel economy goes down because the cruise allows the car to pick up a little speed going down the grade (this is okay, I can accept this) but when it gets to the bottom it allows the car to fall under the set speed by 4-6 MPH then it engages the electric motor and races to catch back up to the set speed and in the process runs over 3-4 MPH.
  • lexusteklexustek Member Posts: 4
    the cruise control system when engauged can be a little jerky.the constant varaible transmission is making literally 100 decisions a sec trying to keep up with your driving requests. the noise you are hearing is the engine rpm coming up to satisfy the voltage needed to move the vehicle faster. it has been noted when cruise is used if you are in a hill terrain will decrease fuel mpg.
  • lexusteklexustek Member Posts: 4
    if you want more power and do more around town driving than highway then test drive a rx400h.
  • wwestwwest Member Posts: 10,706
    You mustn't forget that just because you can "see" the bottom of the downhill slope upcoming the cruise control cannot, it must want for the vehicle speed to begin to decline before it "decides" to go from regenerativge "braking" to ICE/motor torque developement.

    And now delay that "transition" decision just a bit in favor of fuel economy and you have a goodly level of personal frustration with cruise control.
  • lxpatellxpatel Member Posts: 34
    RX400h the battery went dead, because the car was sitting in garage for a month, Lexus sent AAA who jump started it, next day it went dead, even after few miles with engine on. I got another jump today, but now Passenger side window and rear dont work and Also the sunroof.

    What is it? Fuses or Relay.

    Note: Also found the Snail skeleton on the battery terminal.
This discussion has been closed.